Generally, the brake for a bicycle, comprising a pair of cantilevers and a pair of mounting bases through which the cantilevers are mounted to the bicycle frame, has hitherto been well-known and called the cantilever brake.
The cantilever brake is so constructed that the mounting bases are fixed to the bicycle frame, for example, the front fork, by welding or other fixing means. The cantilevers are mounted rotatably to the respective mounting bases, return springs are interposed between the cantilevers and the respective mounting bases, and a suspension wire connecting free ends of both the cantilevers is pulled at the center, so that the cantilevers are rotated against the return springs to bring brake shoes at the cantilevers into contact with the bicycle wheel rim to exert the braking action and the cantilevers being restored by the return springs to release the braking action.
The conventional cantilever brake, however, has each return spring R interposed between a mounting base M and a boss B of cantilever C and exposed to the exterior as shown in FIG. 7. In addition, in the same drawing, reference S designates a shaft mounted to the mounting base M, P designates a pin constituting a rotation restriction means to be discussed below, T designates a through bore provided at the boss B, D designates a projection constituting the rotation restriction means in cooperation with the pin P, E designates a tightening screw, and F designates a washer. Therefore, the return springs R become soiled with mud splashed, for example, by rotation of the bicycle front wheel, or they become dusty, or they get rusty, thereby creating an unsmooth operation of the cantilevers.